In the manufacture of integrated circuits the continuing attempt is to increase transistor density on a substrate of semiconductor material. In this pursuit of higher density, leakage current between transistors has been a problem. One solution to this problem has been the use of channel stop regions which surround each transistor for the purpose of preventing leakage current between transistors. For example, insulated gate field effect transistors can be separated from each other by channel stop regions of the same conductivity type as that of the substrate but of a higher concentration of dopant than that of the substrate. This reduces the leakage current because in the existing art, the channel stop region adjoins the drain or source of the IGFET formed in the active region. The existence of a higher concentration of dopant in the channel stop region, however, creates a reverse biased P-N junction which is stronger than that which would normally exist. Because the channel stop region has a higher concentration of dopant than that of the substrate, the capacitance between the channel stop region and the drain or source is also greater than that of the capacitance between drain or source and the substrate. This increased capacitance has the adverse effect of slowing down the switching speed of the transistor.
In one type of insulated silicon gate field effect transistor technology, polysilicon lines across the surface are used also as electrical conductors between transistors. These polysilicon lines are an additional source of capacitance. To minimize this capacitance, design practice requires that polysilicon lines be laterally offset from adjacent transistors. This has the detrimental effect of decreasing transistor density.